{"id":"CVE-2026-55580","state":"PUBLISHED","title":"mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist","description":"mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, config.go initializes Security.Enabled to false, and when MCP_SHELL_SEC_CONFIG_FILE is unset, main.go starts the documented bare-binary deployment without a security policy. SecurityValidator.validateCommand in security.go then short-circuits and allows every command supplied to the shell_exec MCP tool, so an LLM connected over stdio can execute unrestricted OS commands as the mcp-shell process user. The README from-source installation and MCP client configuration omit MCP_SHELL_SEC_CONFIG_FILE, making the insecure state the documented default. This issue is fixed in version 0.6.0.","publishedAt":"2026-08-25T15:42:36.474Z","updatedAt":"2026-08-25T16:08:10.442Z","severity":{"score":8.6,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["sonirico mcp-shell"],"affected":[{"vendor":"sonirico","product":"mcp-shell","versions":[{"version":"< 0.6.0","status":"affected"}]}],"references":["https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m","https://github.com/sonirico/mcp-shell/pull/16","https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f","https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0"],"weaknesses":["CWE-78"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55580.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55580","state":"PUBLISHED","datePublished":"2026-08-25T15:42:36.474Z","dateUpdated":"2026-08-25T16:08:10.442Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T23:18:03.169Z"},"containers":{"cna":{"title":"mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist","descriptions":[{"lang":"en","value":"mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, config.go initializes Security.Enabled to false, and when MCP_SHELL_SEC_CONFIG_FILE is unset, main.go starts the documented bare-binary deployment without a security policy. SecurityValidator.validateCommand in security.go then short-circuits and allows every command supplied to the shell_exec MCP tool, so an LLM connected over stdio can execute unrestricted OS commands as the mcp-shell process user. The README from-source installation and MCP client configuration omit MCP_SHELL_SEC_CONFIG_FILE, making the insecure state the documented default. This issue is fixed in version 0.6.0."}],"affected":[{"vendor":"sonirico","product":"mcp-shell","versions":[{"version":"< 0.6.0","status":"affected"}]}],"references":[{"url":"https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m","name":"https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/sonirico/mcp-shell/pull/16","name":"https://github.com/sonirico/mcp-shell/pull/16","tags":["x_refsource_MISC"]},{"url":"https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f","name":"https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f","tags":["x_refsource_MISC"]},{"url":"https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0","name":"https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.6,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-78","lang":"en","description":"CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-25T15:42:36.474Z"},"source":{"advisory":"GHSA-f5pj-2738-996m","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-25T16:07:52.580459Z","id":"CVE-2026-55580","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-25T16:08:10.442Z"}}]}}}